The present invention relates to a thermal transfer image-receiving sheet, and more particularly to a thermal transfer image-receiving sheet which can realize composite recording on both sides of the thermal transfer image-receiving sheet respectively by a plurality of types of image forming means.
In recent years, the adoption of a sublimation dye thermal transfer method could have enabled high-quality, high-definition images comparable to conventional silver salt photography to be simply realized. Printing of sublimation dye transfer images on postcards in a picture postcard manner followed by mailing or posting has also become widely adopted. In using the prints as postcards, printing of address, name and the like on the backside thereof is necessary. The backside of conventional image-receiving papers generally has no problem of writing with writing implements, but on the other hand, in printing by means of various printers (particularly ink jet printers), problems occur such as feathering of prints and slow drying of printed portions.
The present invention has been made with a view to solving the above problems of the prior art, and it is an object of the present invention to provide a thermal transfer image-receiving sheet which can realize composite recording on both sides of the thermal transfer image-receiving sheet by image formation respectively by means of a sublimation dye thermal transfer method and, in addition, by printing means different from the sublimation dye thermal transfer method.
It is another object of the present invention to provide a thermal transfer image-receiving sheet of which the backside has properties suitable particularly for printing of addresses and names by means of ink jet printers.
As described above, in recent years, the adoption of a sublimation dye thermal transfer method could have enabled high-quality, high-definition images comparable to conventional silver salt photography to be simply realized. Printing of sublimation dye transfer images on papers of postcard size followed by mailing or posting in a picture postcard manner has also become widely adopted. In using the prints as postcards, printing of address, name and the like on and the application of postage stamps to the backside thereof are necessary. Conventional methods for imparting writing quality to the backside of image-receiving sheets are described, for example, in Japanese Patent Laid-Open Nos. 239036/1994, 175052/1997, and 175048/1997, that is, include a method wherein a porous layer is formed using a hydrophilic filler on the backside of a thermal transfer image-receiving sheet, and a method wherein fine concaves and convexes are formed using a hard filler or a hard resin to render the backside suitable for writing. In general, however, the conventional methods pose no problem of writing with writing implements, but on the other hand, in printing by means of ink jet printers, problems occur such as feathering of prints and slow drying of printed portions. Further, when commercially available inks for ink jet printers are used, these inks are different from each other or one another in ink composition and solvent composition according to makers. For this reason, the level of feathering after printing varies depending upon inks, and, thus, it is difficult to provide even print quality.
In general, an ink-receptive layer should be very thickly coated on a substrate so that the ink composition ejected by ink jetting can be absorbed in the sheet. Therefore, in production equipment, such as gravure coaters or bar coaters which can be advantageously applied in the case of small coverage, it is difficult to provide any layer which enables ink jet printing. In addition, since fine concaves and convexes are formed to impart writing quality, for some level of concaves and convexes, the quality of thermal transfer image-receiving sheets is deteriorated.
In addition to writing quality, smaller friction against image-receiving face to realize stable paper feeding or delivery is required of the backside of thermal transfer image-receiving sheets. To this end, for example, Japanese Patent Laid-Open Nos. 101163/1995 and 223384/1995 disclose methods for reducing friction through the utilization of specific fillers or resins. These conventional methods can provide excellent paper feed and delivery properties. In these methods, however, it is difficult to simultaneously impart excellent paper feed properties and satisfactory writing quality and adhesion to postage stamps.
Accordingly, it is a further object of the present invention to provide a thermal transfer image-receiving sheet which, without causing a deterioration in quality attributable to concaves and convexes provided on the backside, can realize, at low coverage, good suitability for printing by means of ink jet printers and writing with various writing implements and, in addition, has satisfactory adhesion to postage stamps, has excellent carriability in printers, and can exhibit stable properties even after storage under high temperature conditions or under high temperature and high humidity conditions.
First Invention
According to a first invention, there is provided a thermal transfer image-receiving sheet comprising: a substrate; a first recording layer provided on one side of the substrate, an image being formable on the first recording layer by a sublimation dye thermal transfer method; and a second recording layer provided on the other side of the substrate and comprising a combination of two or more layers, said second recording layer permitting recording to be made by printing means other than the sublimation dye thermal transfer method, whereby composite recording can be made on both sides of the thermal transfer image-receiving sheet respectively by a plurality of types of image forming means.
According to a preferred embodiment of the present invention, the second recording layer comprises an absorption layer and a fixation layer provided in that order on the substrate to constitute a composite layer. The fixation layer in the second recording layer preferably comprises a polyvinyl acetal resin and a nylon filler.
The absorption layer in the second recording layer preferably comprises a polyvinyl butyral resin and a filler.
The second recording layer in the thermal transfer image-receiving sheet according to the present invention is particularly suitable for printing by ink jet recording and is further applied, for example, as a recording layer for thermal ink transfer or as a recording layer for electrophotography.
Second Invention
According to a second invention, there is provided a thermal transfer image-receiving sheet comprising a substrate sheet; a dye-receptive layer provided on at least one side of the substrate sheet; a hydrophilic porous layer (an absorption layer) provided on the substrate sheet in its side remote from the dye-receptive layer, said hydrophilic porous layer being composed mainly of a thermoplastic resin and hydrophilic porous particles; and a backside coating (a fixation layer) provided on the surface of the hydrophilic porous layer, said backside coating comprising a polyvinyl acetal resin, a silicone-modified acrylic resin, and nylon resin particles.
In the second invention, the content of the silicone-modified acrylic resin is preferably 5 to 35% by weight based on the total solid content of the backside coating.
Preferably, the nylon resin particles (nylon filler) have an average particle diameter of 5 to 20 xcexcm and the weight ratio of the nylon resin particles to the resin in the backside coating is 0.25 to 2.0.
The thermoplastic resin in the hydrophilic porous layer is preferably a polyvinyl butyral resin or a polyvinyl acetal resin.